Question

As given by the figure, the internal volume is 400 a building with m', an electrical power of 30 kW is heated by the heater. Electric heater adiabatic the canal is inside the canal. Initially, the air inside the building was at 14°C and atmospheric pressure at the building location is 95 It is worth kPa. 450 kJ per minute from the building out heat output. The air inside the channel 250 W to the duct inlet for proper distribution a power fan is also installed. With channel output The temperature difference between the inlet is 5 °C. In order for the building to have an average internal temperature of 24°C. the time to pass by [s] and on the channel Calculate the average flow of air as [kg/s)

Answer 1

Sole 1 T2= Tu +5°c V-400 m3 P=95 kPa We 14°C 24°C Ta 250 W assume We air to be an ideal gas with constant specific heats at room temporature Cp = 1. 005 ks l bg k and w = 0.718 kJ Ilgok. The total man of air in the house is :- m = RT1 - (95 X 10) (400) 287 x (273+ 14) 461.34 kg

We 2 ay take the entire house our system time required to raise the air temperature to the conservation (a) The 24°c is determined by applying of energy relation to this closed volume Systein AU= Wnt Wigan - Q m. Cu (T2-T2)=( Wint Wigan- :) At At = mc, (Ti-T2) Win + Wigan- At- 461.34 X 0.718 x (24-14) (4 out) 30 +0.25 - lota 145.6s 16 ) air through The average mass flow rate of air the duct is determined by applying the Steady flow energy equation to the duct.

3 ma in hy & Wefan + wina miha Wifan + win (h2 ha) Wi fant wn Cp ( 2-Ts) mi m 1) 0.25 + 30 1.005 X 5 ni = 6.02 kgls Completed